Stuttering/Sputtering Issue - Low RPMs

Nismo907

So I've been having an issue with my Z for the past few weeks and I can't seem to pinpoint the issue.

The issue is in the title "Sputtering/Stuttering at low RPMs" regardless of gear.

So it just happened one day about 2-3 weeks ago. I'm gonna clear up a lot of the processes I've been through so far so hopefully I can find a solution.

I've got a '14 370Z sport model. I've modded it with the AEM Cold Air Intake, Stillen Ceramic Coated Headers, Berk Tech Hi-Flow CATs, ARK Exhaust.
More recently I had a tune and everything ran fine. I had to put it away for the winter after having only driven it for 2 weeks after the tune. The issue that came up showed up one day driving from 1 job location to another(about 2-3 weeks ago). No clue what happened. Just acted funny.

So everything that I've done:
- go to the Nissan dealership and(had the tune removed from the tuner and reverted back to factory tune) and updated the firmware on the ECM. Apparently there was an update necessary to fix some issues.
- Put Heet into the fuel as it might have accumulated some water during the winter.... though it was in a garage during the winter.
- Checked my spark plugs, clean.
- Checked my Coil Packs, good.
- Checked my air filters and pre filters. Clean.
- Checked and cleaned my MAF sensors.
- Checked any wires to see if there was any corrosion. All good.

The weird part WAS no check engine light when I first took it to Nissan. After they updated it, I drove it around a bit and it still had the same issue and the check engine light came on and it put into a Limp Mode.

Next day I took off the bumper and cleaned the sensors again, checked to see if there was anything in the sensor, reinstalled after(waited about an hour with the battery unplugged). Started it up, drove it. Does the same thing, but not as harsh or as often. There is no check engine light anymore and I drove it around for like 30-40 minutes at varying speeds up to highway speeds.

So I'm having a hard time trying to narrow down potential issues. I was planning on installing the stock intake again and test it that way. Nissan isn't willing to work with me because of the CAI.

Any ideas?